Polymorphonuclear leukocytes (PMN) are the most numerous host cells found in periodontal pockets and acute inflammatory lesions. Their recruitment and function is considered crucial to the prevention of periodontal attachment loss and the systemic prevention of infection. For example, individuals with compromised neutrophil function or numbers, e.g., in Chediak-Higashi syndrome or neutropenia have increased prevalence and severity of periodontal disease. Little is known about gene expression in PMN because, until recently, mature PMN were not considered capable of synthesizing new protein mediators and thus, unable to actively regulate inflammatory processes. Recent evidence from our laboratory and others, demonstrates that PMN are capable of expressing several important genes in response to agents that prime PMN for increased oxidative metabolism. Therefore, we formulated the hypothesis that agents known to induce increase oxidative metabolism in PMN, e.g., chemotactic factors and cytokines, also induced limited gene expression in PMN. In order to address this hypothesis, we propose to: 1) Characterize the chemotactic factor (fmlp and C5a) and cytokine (Il-1 and TNF) induction of mRNA expression of genes associated with PMN function including a) cytokines known to be inducible in PMN. b) genes associated with PMN activation, i.e., c-fos, c-jun, myristoylated, alanine-rich C kinase substrate. c) genes associated with PMN granules, e.g., gelatinase, elastase, and defensin. 2) Examine the repertoire of chemotactic factor and cytokine induced gene expression a) at the protein level with polyacrylamide gel electrophoresis of radiolabelled newly synthesized proteins. b) at the molecular level by constructing and screening cDNA libraries from induced PMN. From these cDNA libraries we expect to identify expression of known genes never before associated with PMN and genes never previously identified. Thus, from these studies, we hope to bring new insight as to the scope of gene expression in PMN and this will provide important clues as to how PMN function may be altered to improve their function in inflammatory exudates, e.g., in periodontal disease.